Manufacture of pig-iron.



Pafemd Feb. n, |902. .1. A. PoTTEn. v MNUFCTURE F PIG IRUN.

(Application led J'lily 11. 1901.)

(Nu Model.)

INVENTOR WITNESSES ya.. a @zal @4k/@mu 407mg No. 693,062. Paumted Feb.Il, |902.

J. A. POTTER.

MANUFAUTURE 0F PIG IRUN.

(Application filed July 11, 1901.

(No Model.) 3 Sheets-Sheet 2.

WITNESSES lINVENTOW m; nonms sans cc mavo-Lawn. WASHINGTON, u, cA

No. 693,062. Patented Feb. Il, |902.

J. A. POTTER.

MANUFACTURE 0F PIG IRON.

(Applicationled July 11, 1901.)

3 S'heets-Sheet 3.

(No Model.)

R O T N E V m WITNESSES 1m: norms Firms cc.. Puoouruo.. wAsumnTN. n. c.

UNITED STATES PATENT OFFICE,

JOHN A. POTTER, OF CAMDEN, NEV JERSEY.

MANUFACTURE OF PIG-IRON.

SPECIFICATION forming part of Letters Patent No. 693,062, dated February11, 1902. Application filed July 11, 1901. Serial No. 67,853, (Nospecimens.)

T0 all whom, t may concern:

Be it known that I, JOHN A. POTTER, of

Camden, Camden county, New Jersey, have invented a new and usefulImprovement in the Manufacture of Pig-Iron, of which the following is afull, clear, and exact'description, reference being had to theaccompanying drawings, forming part of this specification, in Which-Figure 1 is a sectional side elevation showing my preferred form ofapparatus. Fig. 2 is a top plan view of the same, partly broken away ;Vand Fig. '3 is a plan view of the hearth with the roof portion removedto illustrate the condition of the material at different points.

My invention relates to the making of cast or pig iron, which issuitable for steel-making in the open-hearth process, being low inmetalloids-such as silicon, carbon, phosphorus, arsenic, and sulfurandis designed to provide an improved process for obtaining the same fromall grades of iron ore or 'from cold or molten pig metal4 high inimpurities or metalloids or from all of these materials combined.

I will first describe my invention as carried out with a continuousreduction of iron ore and without the use of additions of pig metalafter the operation has been started.

In the drawings, in which I show my preferred form of apparatus forcarrying out the process, 2 represents an annular hearth mounted uponbearings 3, which I have shown as provided with antifriction-balls 4,interposed between the annular casting 5, which forms the base of thehearth, and a supporting-track 6. The furnace is set at an incline, sothat upon one side it is considerably lower than at the opposite side. Aroof 7 of annular form is supported above the hearth by means of beams8, projecting from a central stack 9. Tie-rods 10 are provided, whichconnect the upper portion of the stack to the outer parts of the beams,these tie-rods being preferably made adjustable, so that the level ofthe roof. may be changed as desired, and for thesame reason the roof ispreferably supported from the beams by means of adjustable hangers 11,secured to the beam. This roof is hollow throughout a major portion ofits length and at a point near the lowest side of the furnace isprovided with a partition 12, on one side of which are providedgas-ports 13 and on the opposite side air-ports 14, both sets of portsopening downwardly upon the hearth. The air enters through a port 15 onone side of a depending roof-shield 17 and flows through the hollow roofin the direction shown by the arrows to the air-ports 14. The gas issupplied through a port 18, adjacent to a vertically-adjustabledepending diaphragm 19, and iiows thence through the hollow roof to thegas-ports 13. The stack-flue 2O leads upwardly from the hearth andthrough the hollow roof to the stack 9, as indicated in Figs. 1 and 2,and between it and the charging-openings 21 and 22 is avertically-sliding depending damper or diaphragm 23, which is similar tothe diaphragm 19. Both of these diaphragme are pret'- erably made hollowand water-cooled by suitable inlet and outlet pipes 24. They may beraised or lowered by chains or flexible connections extending to theloops 25 upon them, and these diaphragme serve to cut 0E the draft fromthose parts of the hearth beneath the charging-openings. The hearth isrotated as desired by means of any suitable connections,

and I have shown its base as provided with a circular rack 26, withwhich intermeshes a pinion 27 on the shaft, to which motion is imparted.The hearth is provided at suitable intervals with tap-holes 28, leadingto spouts or fore-plates 29.

In carrying out my improved process the bottom of the furnace is formedof ordinary refractory material, such as magnesite or dolomite, and thefurnace is heated by means of the preheated air and gases, which enterthe hearth-chamber at the gas and air ports near the low side and thencirculate around to the stack-fine. In starting the furnace I charge inthrough the opening 21 a quantity of pig-iron--say two or three tons. Ithen charge in through opening 22 a thin layer of carbonaceous and limematerials-such as coke-dust, fine coal,charcoal, limestone,&c.- thisbeing discharged upon the bottom immediately in the rear of thepig-iron, and as the bottom of the furnace is moved forward underopening 21 I charge upon these carbonaceous and lime materials a layerof iron ore of any desirable thickness-for example,

six inches. The furnace-bottom is then turned forward intermittently,and charges of carbonaceous andlimey materials,together with layers ofore, are successively charged upon the successive portions of the hearthwhich are brought beneath the chargingopenings. The pig-iron isgradually heated, and when it reaches the hotter zones of the furnace itmelts and envelops,covers,and dissolves the highly-heated iron orecharged in the rear of it. It will be noted that before the iron ore isthus absorbed it will have been slowly rotated into hotter zones andlargely freed from its moisture, sulfur, arsenic, dac., by its exposureto the oxidizing conditions duringits travel from its chargingopening tothe reducing and melting zone. As the furnace is again turned the liquidvmetal Will flow over and cover another portion of the ore which sticksto the bottom of the furnace and is carried beneath it, and after theore is dissolved the carbonaceous and basic materials charged under theore are set free and Will rise up andinto the liquid bath. The carbonwill then be absorbed by the liquid metal, While the lime Will associatewith the silica and phosphorus, duc., in the ore and form a basic slag.The carbon thus added to the hearth will replace the carbon of the pigmetal Which has been consumed by uniting with the oxygen of the ore. Asthe bath of liquid iron becomes increased in bulk a portion of it isdrawn off from time to time, as desired, as is also the slag, and theoperation is made continuous by carrying successive portions of thebasic material, carbon, lime, and ore into and beneath the molten bat-hand tapping off portions of the bath as it increases in size. The hearthafter it passes through the bath will be substantiallybare and will beagain supplied with the materials at the charging-points 22 2l. Thecarbon contained in the liquid bath is utilized to combine with theoxygen in the ore as it washes over and submerges the successiveportions thereof, and to keep it up to the desired percentage necessaryto carry on the reduction and keep the bath liquid the carbon is addedto the materials charged in any desirable amount.

In working finely divided ores they are mixed with the lime and carbonand the Whole mixture charged in on the furnace-bottom. In this case Ihave found by experiment that when lime is present with carbon and oxidof iron a iiux is sometimes formed before the oxygen has been removedfrom the ore. This is due to the combining of the lime and silica at alower temperature than that necessary to reduce iron ore to metallics,and to prevent this fluxin g from taking place I propose charging withthis finely-divided ore suflicient carbon to reduce the oxygen containedin the ore. I would then also place on the bottom of the furnace limeand carbonoceous matter, as outlined above, to act as a recarburizer forthe liquid metal and a iux for the silica after the metal has beenreduced. v

. Instead of charging only iron ores With or ou carbon and basicmaterials I may operate the process by adding successive portions ofmolten pig-iron through a hole 30 in the roof at the low side of thefurnace or through a top hole on the ascending side of the furnace.

In this case molten pig metal is charged into the low side of thefurnace to form a bath at this point. carbon, if desired) are thencharged in upon the hearth at the charging-openings, and as the bottomis turned the mixture will be carried into roasting zones of increasingtemperature and finally be carried beneath the -molten metal, ywhichwill -ilow over the ore and absorb the metal in it, as above described.The molten metal will thus be reduced in carbon, dac., and the metalextracted from the ore. The molten product can be partially or Whollydrawn off and a new charge of molten metal poured in.

If it is desired to use scrap, cold pig, dac., in the process, the ore,lime, and carbonaceous matter may be charged, if desired, and the pig,scrap, dac., then charged upon it, these successive charges beingcarried into and under the bath, as before. The process used with thesuccessive additions of molten pig is especially desirable in making aniron low in silicon, phosphorus, and carbon for use in the acidopen-hearth furnaces, the metal being taken liquid directly from therevolv ing furnace to the open-hearth furnace. The amount of carbon inthe irontapped from the revolving furnace may be regulated by the amountof carbonaceous matter charged With or under the ore. This carbonaceousmatter may be omitted at intervals, so that at certain periods theliquid bath would not be rec'arburized and would become low in carbonbefore tapping off, thus making this process very desirable inconnection with the openhearth process. By this process iron-ore ormetal high in sulfur, phosphorus, and other impurities may be utilizedfor steel, thus making ores of this character available for openhearthpractice.

The advantages of my invention are many. The operation is continuousbymeans of the carrying of successive Ypbrtions'of ore and basic materialbeneath the liquid bath of iron. The basic slag thus formed carries offthe impur rities and metalloids,and carbon is supplied to the bath asdesired to replace that consumed by uniting the oxygen with the ore. Theore Will adhere to the bottom of the furnace by becoming pasty and willthus be carried down under the liquid bath, the best conditions beingthus provided for its complete reduction and the absorption of the metalcontained in the ore. The carbon-gases formed during preheating of theore and charge will associate v4with the oxygen of the ore and aid inpreparing it for reduction, the reducing-gas acting Iron ore and basicmaterial (or ICO IIG

eeaoesA as in a blast-furnace, where the gases rise through the charge.

Many variations may be made in the apparatus employed, as Well as in thematerials 5 used, Without departing from my invention.

I claim- 1. The method of reducing iron ore,consist ing in forming abath of molten pig-iron and carrying into and under said bath a mixtureof iron ore and basic material, substantially as described.

2. The method of reducing iron ore,consist ing in forming a bath ofpig-iron and carrying iron ore, carbonaceous material and basic materialinto and under said bath, substantially as described.

3. The method of reducingiron ore,consist ingin successively carryingbeneath a bath of molten pig-iron successive additions of iron ore andbasic material, substantially as de- 4. The method of reducing ironore,consist ing in forming a bath of molten pig-iron upon a continuoushearth, carrying successive por- 25 tions of iron ore, carbon and basicmaterial on the hearth into and under the bath, and feeding suchmaterial to successive portions of the hearth, substantially asdescribed.

5. The method of reducing iron ore,consist iugin forming a bath ofmolten pig-iron, submerging iron orc and basic material in said bath,tapping out the bath, replacing it with fresh molten pig-iron, andcarrying a further supply of ore and basic material into and under saidbath, substantially as described.

6. The method of reducing iron ore,consist ing in forming a molten bathof pig-iron upon one portion of a continuous hearth, adding iron ore andbasic material to the hearth, carrying them into and under the liquidbath, tapping oft a portion of the bath, and continuing the additions ofore and basic material,

substantially as described.

In testimony whereof I have hereunto set my hand.

JOHN A. POTTER.

Witnesses:

JOHN STILLE, ELEANOR STILL.

